Printing something, leaving larger space

Printing something, leaving larger space

Is it possible to use something like \myphantom[xyz]{abcdef} to print "xyz" with some alignment, but leaving space as if it were "abcdef"?
A code like:
\[mn xyz \myphantom[printed]{abcdefghi abcdefghi abcdefghi} 123 456\]
\[mn xyz abcdefghi abcdefghi abcdefghi 123 456\]
To print something like this:
mn printed                       123 456
mn abcdefghi abcdefghi abcdefghi 123 456
Or:
mn                       printed 123 456
mn abcdefghi abcdefghi abcdefghi 123 456
Or:
mn              printed          123 456
mn abcdefghi abcdefghi abcdefghi 123 456
thank you